NO. You are not allowed to modify any Google code what so ever. You can wrap code around the code, but you can not modify the actual AdSense code. You risk getting banned and losing your account for ever.

NO. You can not sign up with more than one AdSense account. By doing so you will break the Google AdSense terms of service, and risk a permanent ban from the program for life.

Google has many mechanisms and tools on their own end to monitor and flag suspicious activity. If a webmaster or blogger clicks their own ads Google can tell almost 99%, if not 100% of the time.

NO. This is a very big no-no when it comes to following AdSense guidelines and Terms of Service.

No. Google will not ban you for having a high CTR, IF you follow these procedures. Let’s put it this way. Google wants you to have a high CTR, why? because a high CTR for you, means Google is making money.

NO. You will not be banned if you make to much money from AdSense. In fact, Google wants you to make money from their system, a real lot. Why? because every time you get a click on your website banner ad, you get paid, along with Google.